Showing papers by "Jalal Abdallah published in 2007"
TL;DR: In this paper, the DELPHI detector at LEP has been used to measure multi-muon bundles originating from cosmic ray interactions with air and the cosmic events were recorded in ''parasitic mode'' between individual e+e- interactions and the total live time of this data taking is equivalent to 1.6x10^6 seconds.
50 citations
TL;DR: In this paper, the results of the investigation of colour reconnection e.g. in fully hadronic decays of W pairs in DELPHI at LEP are presented and two complementary analyses are performed, studying the particle.
Abstract: In the reaction e(+)e(-) -> WW -> (q(1) (q) over bar (2))(q(3)(q) over bar (4)) the usual hadronization models treat the colour singlets q(1)(q) over bar (2) and q(3)(q) over bar (4) coming from two W bosons independently. However, since the. nal state partons may coexist in space and time, cross-talk between the two evolving hadronic systems may be possible during fragmentation through soft gluon exchange. This e. ect is known as colour reconnection. In this article the results of the investigation of colour reconnection e. ects in fully hadronic decays of W pairs in DELPHI at LEP are presented. Two complementary analyses were performed, studying the particle. ow between jets and W mass estimators, with negligible correlation between them, and the results were combined and compared to models. In the framework of the SK-I model, the value for its. parameter most compatible with the data was found to be: (SK)-S-kappa-I = 2.2(-1.3) (+2.5) corresponding to the probability of reconnection P-reco to be in the range 0.31 < P-reco < 0.68 at 68% confidence level with its best value at 0.52.
20 citations
TL;DR: In this paper, the DELPHI detector was used to study neutral triple-gauge-boson couplings ZZZ, ZZγ and Zγγ with data at energies between 183 and 208 GeV.
Abstract: Neutral triple-gauge-boson couplings ZZZ, ZZγ and Zγγ have been studied with the DELPHI detector using data at energies between 183 and 208 GeV. Limits are derived on these couplings from an analysis of the reactions e+e-→Zγ, using data from the final states γff, with f=q or ν, from e+e-→ZZ, using data from the four-fermion final states qqqq, qqμ+μ-, qqe+e-, qqνν, μ+μ-νν and e+e-νν, and from e+e-→Zγ*, in which the final state γ is off mass-shell, using data from the four-fermion final states qqe+e- and qqμ+μ-. No evidence for the presence of such couplings is observed, in agreement with the predictions of the Standard Model.
19 citations
TL;DR: In this article, the results of the investigation of colour reconnection effects in fully hadronic decays of W pairs in DELPHI at LEP are presented, and two complementary analyses are performed, studying the particle flow between jets and W mass estimators, with negligible correlation between them, and the results were combined and compared to models.
Abstract: In the reaction e+e- -> WW -> (q_1 qbar_2)(q_3 qbar_4) the usual hadronization models treat the colour singlets q_1 qbar_2 and q_3 qbar_4 coming from two W bosons independently. However, since the final state partons may coexist in space and time, cross-talk between the two evolving hadronic systems may be possible during fragmentation through soft gluon exchange. This effect is known as Colour Reconnection. In this article the results of the investigation of Colour Reconnection effects in fully hadronic decays of W pairs in DELPHI at LEP are presented. Two complementary analyses were performed, studying the particle flow between jets and W mass estimators, with negligible correlation between them, and the results were combined and compared to models. In the framework of the SK-I model, the value for its kappa parameter most compatible with the data was found to be: kappa_{SK-I} = 2.2^{+2.5}_{-1.3} corresponding to the probability of reconnection P_{reco} to be in the range 0.31 < P_{reco} < 0.68 at 68% confidence level with its best value at 0.52.
11 citations
TL;DR: The performance of two algorithms currently running in the Tile Calorimeter Read-Out Driver boards for the commissioning of ATLAS, the so called Optimal Filtering and the MTag which tags low transverse momentum muons that may escape the ATLAS muon spectrometer first level trigger are presented.
Abstract: In this paper we present the performance of two algorithms currently running in the Tile Calorimeter Read-Out Driver boards for the commissioning of ATLAS. The first algorithm presented is the so called Optimal Filtering. It reconstructs the deposited energy in the Tile Calorimeter and the arrival time of the data. The second algorithm is the MTag which tags low transverse momentum muons that may escape the ATLAS muon spectrometer first level trigger. Comparisons between online (inside the Read-Out Drivers) and offline implementations are done with an agreement around 99% for the reconstruction of the amplitude using the Optimal Filtering algorithm and a coincidende of 93% between the offline and online tagged muons for the MTag algorithm. The processing time is measured for both algorithms running together with a resulting time of 59.2 μs which, although above the 10 μs of the first level trigger, it fulfills the requirements of the commissioning trigger ( ~ 1 Hz). We expect further optimizations of the algorithms which will reduce their processing time below 10 μs.
7 citations
TL;DR: In this paper, a search for pentaquarks is described using the DELPHI detector at LEP, characterized by powerful particle identification sub-systems crucial in the separation of the signal from the background for these states.
6 citations
TL;DR: In this article, a search for the pair production of fourth generation b'-quarks was performed using data taken by the DELPHI detector at LEP-II, where the analysed data were collected at centre-of-mass energies ranging from 196 to 209 GeV, corresponding to an integrated luminosity of 420 pb(-1).
Abstract: A search for the pair production of fourth generation b'-quarks was performed using data taken by the DELPHI detector at LEP-II. The analysed data were collected at centre-of-mass energies ranging from 196 to 209 GeV, corresponding to an integrated luminosity of 420 pb(-1). No evidence for a signal was found. Upper limits on BR(b'-> bZ) and BR(b'-> bZ) were obtained for b' masses ranging from 96 to 103 GeV/c(2) stop. These limits, together with the theoretical branching ratios predicted by a sequential four generations model, were used to constrain the value of R-CKM=vertical bar V-cb(') /V-tb'V-tb vertical bar there V-cb', V-tb' and V-tb are elements of the extended CKM matrix.
2 citations
TL;DR: The Optical Multiplexer Board is a card included in the TileCal Data Acquisition System; it is designed to receive two optical fibers with same data from front-end boards and decided which has correct data.
Abstract: The Optical Multiplexer Board is a card included in the TileCal Data Acquisition System; it is designed to receive two optical fibers with same data from front-end boards and decided which has correct data. Inside this card we have different transmission lines that need to be studied; signal integrity problems such as signal delay, reflection, distortion and coupling should be analyzed. This paper presents the results of the signal integrity studies at the Optical Multiplexer Board for TileCal System.
1 citations
TL;DR: In this article, the DELPHI detector has been used to measure Z gamma* production at center-of-mass energies ranging from 183 to 209 GeV, corresponding to an integrated luminosity of about 667 pb(-1).
Abstract: Measurements of Z gamma* production are presented using data collected by the DELPHI detector at centre-of-mass energies ranging from 183 to 209 GeV, corresponding to an integrated luminosity of about 667 pb(-1). The measurements cover a wide range of the possible final state four-fermion configurations: hadronic and leptonic (e(+) e(-) q (q) over bar, mu(+) mu(-) q (q) over bar ,q (q) over barv (v) over bar), fully leptonic (l(+) l(-) l' (+) l'(-)) and fully hadronic. nal states (q (q) over barq (q) over bar, with a low mass q (q$) over bar pair). Measurements of the Z gamma* cross-section for the various. nal states have been compared with the Standard Model expectations and found to be consistent within the errors. In addition, a total cross-section measurement of the l(+) l(-) l'(+)l'(-) cross-section is reported, and found to be in agreement with the prediction of the Standard Model.
1 citations
01 Oct 2007
TL;DR: It is detailed the Detector and Verification System (DVS) tests and TileCal calibration runs performed with RODs during the three commissioning phases and the ROD system installation in the ATLAS electronics cavern.
Abstract: TileCal is the hadronic tile calorimeter of the ATLAS experiment at LHC/CERN. The main component of the TileCal back-end electronics is the Read-Out Driver (ROD). The ROD system is placed between the first and the second level trigger and it is the responsible for processing the data gathered by the detector. The principal devices of the RODs are the Digital Signal Processors (DSPs) mounted in the Processing Units (PUs) daughterboards. The architecture and functionality of the RODs are briefly explained. Then, it is presented the ROD system installation in the ATLAS electronics cavern. Currently, the RODs are being used for the detector commissioning. It is detailed the Detector and Verification System (DVS) tests and TileCal calibration runs performed with RODs during the three commissioning phases.